Site U1517

Data report: 87Sr/86Sr in pore fluids from IODP Expeditions 372 and 375, Hikurangi margin.

“…Strontium concentration and 87 Sr/ 86 Sr isotopic ratio measured in pore fluids from Sites U1517-U1520. Lithologic units and ages correspond to those from Barnes et al (2019aBarnes et al ( , 2019bBarnes et al ( , 2019c and Saffer et al (2019). ceous sediment of Units V and VI, dissolved strontium concentration increases from 153.65 μM at 972.0 mbsf to 218.67 μM at the bottom of the hole.…”

“…The composition and lithostratigraphy of the sediment recovered during Expeditions 372 and 375 were described by the shipboard sedimentologists. Site U1517 is detailed in Barnes et al (2019a), and sediment from the additional sites are described in the Site U1518, Site U1519, and Site U1520 chapters (Saffer et al, 2019;Barnes et al, 2019bBarnes et al, , 2019c. We briefly summarize their results to provide context for the strontium data presented here.…”

Expedition 372B/375 summary

“…The SMTZ is marked by a concomitant increase in headspace methane concentration from 51 to 5461 parts per million by volume (ppmv). The SMTZ is shallower at this site than at nearby Site U1517 (drilled during Expedition 372 [Barnes et al, 2019a]), which likely indicates a larger vertical methane flux. Ethane was detected in some headspace samples shallower than 200 mbsf but was not detected deeper.…”

Data report: standard mineral mixtures, normalization factors, and determination of error for quantitative X-ray diffraction analyses of bulk powders and clay-sized mineral assemblages

“…As a final test of accuracy, we have the benefit of comparing the computed XRD weight percent calcite values versus percent carbonate values, as determined independently by shipboard coulometric analysis (for methods, see Wallace et al, 2019). The comparisons for Sites U1517 and U1520 (for tabulated data, see Barnes et al, 2019a) are shown in Figure F12, based on JR-MD results and the corresponding polynomial regressions. The full range of compositional possibility is relatively small at Site U1517, with most of the hemipelagic mud specimens clustering between 5% and 15% calcite.…”

“…Figure F12. Independent tests of absolute accuracy using results from natural specimens, Sites U1517 and U1520 (for tabulated data, see Barnes et al, 2019aBarnes et al, , 2019b. Crossplots show percent carbonate from shipboard coulometric analyses versus X-ray diffraction (XRD)-derived weight percent calcite in same specimens.…”